1. Field of the Invention
The present invention relates to an improvement in an autoanalyzer that samples a specimen by using a probe to perform biochemical analysis and immunological analysis with respect to the specimen, and in a probe cleaning method of cleaning the probe used in the autoanalyzer.
2. Description of the Related Art
An autoanalyzer is provided in, e.g., hospitals. The autoanalyzer analyzes a specimen, e.g., blood or urine in accordance with each inspection item. The autoanalyzer is constituted by coupling a biochemical analysis unit that performs biochemical analysis with respect to a specimen and an immunological analysis unit that carries out immunological analysis. The autoanalyzer accommodates a specimen in a specimen container, and carries this specimen container between the biochemical analysis unit and the immunological analysis unit by using a carriage system.
A reaction tube is provided in each of the biochemical analysis unit and the immunological analysis unit. The reaction tube is carried by the carriage system. When the reaction tube is carried to the biochemical analysis unit or the immunological analysis unit, the specimen in the specimen container is divided and poured into the reaction tube in each of the biochemical analysis unit and the immunological analysis unit. Divided pouring is carried out by each sampling mechanism provided in each of the biochemical analysis unit and the immunological analysis unit. Each sampling mechanism is constituted by, e.g., providing a sampling probe to a sampling arm. The sampling mechanism immerses the sampling probe in the specimen in the specimen container by driving the sampling arm, sucks the specimen in the specimen container by the sampling probe, moves the sampling probe into the reaction tube, and discharges the specimen into the reaction tube from the sampling probe.
The autoanalyzer sequentially carries the plurality of specimen containers accommodating different specimens therein to the biochemical analysis unit and the immunological analysis unit to divide and pour the specimens into the respective reaction tubes. Therefore, as shown in FIG. 15, the sampling probe is cleaned to avoid contamination between the previous specimen and the next specimen, i.e., carry-over. The sampling probe is cleaned after the specimen is sucked to be discharged into the reaction tube. As a result, in regard to an amount of a residue of the sampling probe, an amount Cb of the residue after cleaning is smaller than an amount Ca of the residue before cleaning as shown in FIG. 15.
As a technology concerning cleaning the sampling probe, there is one disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2004-251797. Jpn. Pat. Appln. KOKAI Publication No. 2004-251797 discloses forming an opening, from which a cleaning liquid is discharged, to include a region where the cleaning liquid discharged toward an outer wall of a sampling probe placed in a cleaned state is immersed in a specimen.
The biochemical analysis unit and the immunological analysis unit have a considerable difference in measurement sensitivity with respect to a specimen. The sensitivity of the immunological analysis unit is higher than that of the biochemical analysis unit. As a result, the biochemical analysis unit does not require high performance in relation to carry-over between specimens. Even if there is carry-over between the previous specimen and the next specimen, the biochemical analysis unit does not affect an analysis result.
On the other hand, the immunological analysis unit requires high performance concerning carry-over between specimens. Therefore, if there is carry-over between the previous specimen and the next specimen, an error in an analysis result occurs in the immunological analysis unit.
Carry-over between specimens is also dependent on a degree of contamination of a sampling probe, conditions under which a specimen is sampled, and others. Therefore, in the existing circumstances, it is difficult to keep the performance requiring the carry-out performance between specimens under all conditions.
It has been confirmed from experiments that the carry-over between specimens vary depending on sampling conditions due to the following tendency. When the number of times of sampling is increased, the carry-over between specimens is also increased. An increase in the number of times of sampling and an increase in the carry-over do not necessarily have a proportionality relation. The carry-over between specimens is increased in accordance with an integration amount of specimens to be sucked by a sampling probe. Here, the integration amount of specimens is a sum total of sampling amounts of all specimens including a dummy and sampling amounts of the first sampling to the nth sampling, for example.
A maximum number of times of sampling in the autoanalyzer exceeds 100 times because of specifications. A sampling probe may suck and discharge a specimen having a sampling amount of, e.g., 35 μL because of its specifications. In such sampling, even if the number of times of sampling is the same as that of sampling having an average sampling amount, e.g., approximately 4 μL, the carry-over between specimens becomes large.
Under two types of sampling conditions, i.e., the number of times of sampling and a sampling amount, a value of the carry-over between specimens required under maximum conditions in specifications is, e.g., 0.1 ppm or below. However, it is difficult to set the value of the carry-over to, e.g., 0.1 ppm or below.
It is an object of the present invention to provide an autoanalyzer that can assure performance requiring carry-over between specimens even if the number of times of sampling or a sampling integration amount of the specimens is increased, and a probe cleaning method.